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Registered User
Join Date: Oct 2006
Location: Chas, SC
Posts: 1,057
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CO/O2 Guru's
As I have stated before, I have a 1986 930 that I have removed all smog equipment, and replaced the cat and muffler with an early 80's euro. (Single pipe, I never liked the dual pipe). I just basically wanted to get rid of all the heat that the cat generates and the smog equip to make servicing easier. I don't track the car, and for right now not going to make any other changes/enhancements. I always run prem fuel. My questions are for the effect of the O2 sensor and CO adjustment. I currently have the O2 disconnected and the CO at 2%. I'd like to know the pros and cons of:
1)Setting the CO back to specs .6 +- .2 and reconnecting the O2 2) Leaving the O2 disconnected and increasing the CO to 3-4% per recomendations from this board. What effect does the O2 have on setting the CO?
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-10-2007, 06:11 PM
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A fellow Pelacanite
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The sensor will try to get your car to run at 0%, that is Stoich. All fuel will be burnt, emmisions will be low, fuel economy good.
The bad news is that our cars like a richer mixture for cooling to preserve the engine... Have you seen pics of pistons eaten by detonation ?
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg Last edited by NathanUK; 02-11-2007 at 12:31 AM.. |
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02-11-2007, 12:14 AM
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Registered User
Join Date: Oct 2006
Location: Chas, SC
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In theory, as long as I don't have detonation, I should not suffer any damage from setting the CO to spec and connecting the O2 ? The reason I am asking is I use this car for long trips (highway) and I'd like to set it to spec for the trips, (gas mileage) then when I am home fatten the CO and disconnect the O2, as that is when I would do more spirited driving.
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-11-2007, 06:34 AM
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A fellow Pelacanite
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Fit a wideband AFR gauge, then you will know what is going on. You cannot hear damaging detonation. Something like the Innovate LM1.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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02-11-2007, 08:29 AM
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Registered User
Join Date: Oct 2006
Location: Chas, SC
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Nathan, Thanks for the consistent replies. I find it hard to believe that setting the CO to spec and running the O2 could possibly damage a stock engine. Going leave the O2 disconnected for now and play with the CO between 2-4% to see where it runs best. I'd really like to be able to run stock specs on trips though, for the mileage....Been looking at the LM-1's may follow that route to really be able to see what it is actually doing. Thanks again for all the help...
Tim.
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-11-2007, 06:42 PM
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Location: Chas, SC
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Can I connect a digital multimeter to the O2 sensor, get a voltage reading then convert to a CO %? Where would I get the conversion table?
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-12-2007, 06:25 AM
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A fellow Pelacanite
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If your car is stock then running with sensor connected should be fine. Checking the AFR's is your answer for peace of mind.
The stock sensor is a narrow band and only good for measuring 0% (stoich). Our engines need approx. 4% at full boost or 12-1 AFR. The stock sensor is not accurate at checking this. Get a wideband setup fitted !
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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02-12-2007, 01:16 PM
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Registered User
Join Date: Feb 2006
Location: charlotte NC
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Tim, what affect has removing cat +stock muffler made? I have an 88 stock that I am considering doing the same vs a test pipe. Any comments? By the way I have a place on IOP, do you do your on wrench or do you use someone in Charleston?
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02-12-2007, 02:43 PM
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Registered User
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Location: Chas, SC
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Brett - Sent you a PM...
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-12-2007, 03:38 PM
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Registered User
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Location: Chas, SC
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Quote:
I'm going to take your advice on the LM-1.... tim.
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Tim 1986 930 Gone:71,2,4 914's, 70T, 71T(RS),77S |
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02-12-2007, 03:43 PM
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Registered User
Join Date: Jul 2006
Location: Valrico Florida
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Regarding the VOM as a monitor on a narroew band O2 sensor; it can be done. I experimented with this years ago on a fuel injected 914. I discovered the maximum power was acheived @ .945 to .985 volts. I had a real-time adjustment in the car. I could set the O2 @ .500 (stoich) and the power was noticably reduced but great milage for the long haul. If I increased the mixture to above .985 the power would again drop off due to over-rich condition. The maximum output voltage of a narrow band 02 is 1.000 volt by design, my Fluke 77 would register 1.006. That's reasonably close. I don't know how the output voltage relates to A/F ratio but I couldn't argue with the seat-of-the-pants real-time test results. Also, be sure the circuit loading is minimal on your test meter. I believe it's at least 100K per volt on the Fluke. An inexpensive meter will not work.
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'77 930 turbo Garretson I/C 1 BAR spring, (2) '82 Triumph Bonneville Royal Wedding Edition Past rides: '74 914 1.9 liter twin plugged track car, '83 928S, '87 924S, '75 911S w '78 ROW 3.0, '72 911T, '70 911T and various other insignificant domestic examples. Happiness is a grey tailpipe! Turbo lag......it's worth the wait! |
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02-12-2007, 04:51 PM
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A fellow Pelacanite
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When the AFR is producing maximum power on boost it can be damaging our engines. We need to go slightly richer. For a NA car it would be fine. At cruise we do not need 12-1 we can go leaner.
Tim, not sure how that would work. Possibly it would spend too much time trying to fight each other and it wouldn't be good for anything.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg Last edited by NathanUK; 02-13-2007 at 02:11 AM.. |
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02-13-2007, 01:43 AM
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